1. Field of the Invention
The present invention relates to UV radiation devices, and in particular to a UV radiation device for treating fluids with a simplified radiation chamber.
2. Background Art
UV radiation devices are known in the art. For example, one UV radiation device is shown in U.S. Pat. No. 4,367,410. There an arrangement, formed from two bulkhead walls and a radiation chamber lying in between which reduces the cross section of the waste water conduit so that the waste water flow to be treated must enter the radiation chamber, is inserted in a gulley of a waste water conduit. A number of lamp units are arranged diagonally to the flow direction in the radiation chamber. The lamp units are in each case arranged above each other in rows in relation to the flow direction. Several rows of lamp units are arranged behind each other in relation to the flow direction.
This known radiation device restricts the cross-section of the waste water conduit which is often undesirable for hydrodynamic reasons. In addition, these devices represent a relatively high technical expense not required by the function of the radiation process itself.
In addition, another radiation device is disclosed in EP 0687201 B1. This reference shows a radiation chamber with radiation sources arranged parallel to the flow direction of the fluid. This configuration is in practice also seen as disadvantageous since the radiation sources with the total lamp unit have to be removed from the conduit for maintenance first in or against the flow direction so that they can be lifted up. In addition, the configuration of lamp units or radiation sources diagonal to the flow direction is advantageous to ensure uniform radiation of the total volume flow.
It is therefore an object of the present invention to create a radiation device with lamp units or radiation sources arranged diagonally to the flow direction which has more favourable hydrodynamic properties and requires much less technical expense.
In the device disclosed and claimed herein, as at least the side walls and the base wall are made from a non-metallic material and the distance between two walls facing each other in the diagonal direction is less or equal to the discharge length of the radiation source, the total cross section bordered by the non-metallic material (generally concrete) is used as the radiation chamber. Elaborate components which must generally be made as stainless steel parts are no longer necessary. The full cross section formed from the non-metallic material continues into the area in which the radiation sources are arranged, without any hydrodynamically disadvantageous constrictions. Therefore, no unnecessary back pressure is built up in the area of a cross section constriction.
Further, it is possible that the lamp units are held by flange plates which are countersunk providing a seal into recesses of the walls. This preferred form of embodiment enables the conduit and the radiation chamber down to minute recesses to be prefabricated in concrete by construction firms on the spot. The structures necessary for the final installation of the radiation device are limited to relatively small sub-assemblies which reduces both the cost of the radiation device itself as well as the transport and assembly expense necessary.
The lamp units can be held on one side in flange plates, whereby the opposite end can be supported in simply formed recesses. Also, it is possible that the lamp units are held by flange plates facing each other which gives accessibility from both sides and good definition of the fitted position. Uniform and intensive radiation of the fluid flow is possible if rows of lamp units are arranged diagonally at a uniform mutual distance and if several rows are provided behind each other in the flow direction. In this case rows following each other in the flow direction can be aligned cross-wise to each other so that turbulence is deliberately induced in the flow. The distance of the two outer lamp units of a row from the next adjacent wall is preferably smaller or equal to half the distance of two adjacent lamp units from each other. In this way, it is ensured that the radiation intensity directly on the wall is also sufficiently high.
Simple maintenance of the radiation sources is made possible if the cover tube of each individual lamp unit is arranged to provide a seal at least in the flange plate on the connection side and the radiation source is to be fitted and removed without dismantling the cover tube. With such a form of embodiment, radiation sources can be replaced during operation without fluid being able to escape at the connection points between the flange plate and the cover tubes. The radiation chamber during operation is preferably under pressure which ensures high flow speeds within the radiation chamber and that the radiation chamber is filled up to the upper limit. Here, the walls of the radiation chamber can be designed in an especially simple way to resist pressure by at least the side walls, preferably also the ceiling wall and the base wall being supported against each other with tension rods running diagonally through the radiation chamber. These tension rods induce further turbulence uniformly distributed over the total radiation chamber, preventing the formation of continuous steady filaments of flow in areas of lesser intensity. The tension rods are preferably provided over the entire length of the radiation chamber and indeed particularly cross-wise horizontally and vertically.
A further improvement of the turbulence in the radiation chamber is achieved when rows of lamp units are staggered behind each other in the flow direction particularly so that a following lamp unit in each case lies in the centre between two lamp units arranged upstream.
To replace radiation sources during normal operation, it is advantageous if the radiation sources are held in the lamp units with brackets and are supplied via an electric connection, the brackets being only accessible when the electric connection is disconnected from the radiation source. Thus, it is ensured that the radiation source not in operation when it gives off UV radiation harmful for humans can be removed from the cover tube. At the same time, this configuration ensures that an individual radiation source can be safely replaced without having to switch off the other radiation sources of the system.